Re: [PATCH v3] x86: Put trampoline in separate .init.trampoline section

[Frediano Ziglio <frediano.ziglio@xxxxxxxxx>]

On Mon, Sep 16, 2024 at 1:29 PM Frediano Ziglio
<frediano.ziglio@xxxxxxxxx> wrote:
>
...
> >
> > Independently, given the adjustment in this patch, we should just make
> > trampoline.o a proper object and take it out of head.S  That's one fewer
> > non-standard moving parts in the build.
> >
>
> I think another hidden assumption is having the possibility to do some
> math on trampoline symbols, and that requires having the source of the
> trampoline combined with the source of head.S. But to remove the
> "think" from the previous sentence, I need to do some test.
>

Okay, there are 2 formulae that requires this, specifically
- (.Ltrampoline_gdt_end - trampoline_gdt)
- (trampoline_boot_cpu_entry - trampoline_start)

just 3 symbols to export (trampoline_start is already exported) and 2
numbers to compute somehow (either linker script exporting absolute
symbols or computing using code).

> > ~Andrew
>

Frediano